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Flexible test stands based on LabVIEW
Tadej Tašner, Darko Lovrec, 2012, izvirni znanstveni članek

Opis: Research departments and laboratories, as well as industry itself need to become more flexible. They need to adopt new trends and technologies as quickly as possible. It is obvious however, that any hardware should be changed minimally in order to reduce costs and the complexities of any changes necessary. Therefore, any update has to be made mainly by software changes. This article introduces a concept of a transmission test ]stand modified into a hydraulic test ]stand, using the same equipment and changed software based on LabVIEW. LabVIEW uses G programming language with block diagrams which is, compared to a text-based program, easier to understand and update.
Ključne besede: LabVIEW, test-stand, transmission, hydraulics, graphic programming
Objavljeno v DKUM: 01.06.2012; Ogledov: 1291; Prenosov: 52
URL Povezava na celotno besedilo

Evolutionary programming of CNC machines
Miha Kovačič, Miran Brezočnik, Ivo Pahole, Jože Balič, Borut Kecelj, 2005, izvirni znanstveni članek

Opis: The paper proposes a new concept for programming of CNC machines. The concept based on genetic algorithms assures evolutionary generation and optimization of NC programs on the basis of CAD models of manufacturing environment. The structure, undergoing simulated evolution, is the population of NC programs. The NC programs control the machine which performs simple elementary motions. During the evolution the machine movement becomes more and more complex and intelligent solutions emerge gradually as a result of the interaction between machine movements and manufacturing environment. The examples of evolutionary programming of CNC lathe and CNC milling machine tool for different complexities of the blanks and products are presented. The proposed concept showed a high degree of universality, efficiency, and reliability and it can be also simply adopted to other CNC machines.
Ključne besede: manufacturing systems, NC-programming, CNC lathes, simulated evolution, genetic algorithms
Objavljeno v DKUM: 01.06.2012; Ogledov: 1724; Prenosov: 106
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Optimum design of plane timber trusses considering joint flexibility
Simon Šilih, Miroslav Premrov, Stojan Kravanja, 2005, izvirni znanstveni članek

Opis: The paper presents the optimization of metal-plate-connected plane timber trusses with special emphasis on joint flexibility. The optimization was performed by the non-linear programming approach. Since various truss design parameters such as type of truss configuration, span/depth ratio, number and type of diagonal and vertical members and type of joint connections simultaneously affect each other, it is proposed that all of these parameters should be considered simultaneously in a single mathematical model. An optimization model for cost optimization of timber trusses was thus developed. The economic objective function for minimizing the structure's self-manufacturing costs was defined, subjected to the design, stress and deflection (in)equality constraints. The finite element equations were as the equality constraints defined for the calculation of the internal forces and the deflections of the structure. The stiffness matrix of the structure was composed by considering fictitiously decreased cross-section areas of all the flexibly connected elements. Constraints for the dimensioning of the timber members were determined in accordance with Eurocode 5 in order to satisfy the requirements of both the ultimate and the serviceability limit states. The cross-section dimensions and the number of fasteners were defined as independent optimization variables. A numerical example demonstrates the applicability of the optimization approach presented as well as the influence of the fasteners' flexibility on the optimal self-manufacturing costs.
Ključne besede: civil engineering, timber structures, trusses, fasteners, flexibility, optimization, non-linear programming
Objavljeno v DKUM: 01.06.2012; Ogledov: 2076; Prenosov: 122
URL Povezava na celotno besedilo

Prediction of maintenance of sinus rhythm after electrical cardioversion of atrial fibrillation by non-deterministic modelling
Petra Žohar, Miha Kovačič, Miran Brezočnik, Matej Podbregar, 2005, izvirni znanstveni članek

Opis: Atrial fibrillation (AF) is the most common rhythm disorder. Because of the high recurrence rate of AF after cardioversion and because of potential side effects of electrical cardioversion, it is clinically important to predict persistence of sinus rhythm after electrical cardioversion before it is attempted. The aim of our study was the development of a mathematical model by"genetic" programming (GP), a non-deterministic modelling technique, which would predict maintenance of sinus rhythm after electrical cardioversion of persistent AF. PATIENTS AND METHODS: Ninety-seven patients with persistent AF lasting more than 48 h, undergoing the first attempt at transthoracic cardioversion were included in this prospective study. Persistence of AF before the cardioversion attempt, amiodarone treatment, left atrial dimension,mean, standard deviation and approximate entropy of ECG R-R intervals were collected. The data of 53 patients were randomly selected from the database and used for GP modelling; the other 44 data sets were used for model testing. RESULTS: In 23 patients sinus rhythm persisted at 3 months. In the other 21 patients sinus rhythm was not achieved or its duration was less than 3 months. The model developed by GP failed to predict maintenance ofsinus rhythm at 3 months in one patient and in six patients falsely predicted maintenance of sinus rhythm. Positive and negative likelihood ratiosof the model for testing data were 4.32 and 0.05, respectively. Using this model 15 of 21 (71.4%) cardioversions not resulting in sinus rhythm at 3 months would have been avoided, whereas 22 of 23 (95.6%) cardioversions resulting in sinus rhythm at 3 months would have been administered. CONCLUSION: This model developed by GP, including clinical data, ECG data from the time-domain and nonlinear dynamics can predict maintenance of sinus rhythm. Further research is needed to explore its utility in the present or anexpanded form.
Ključne besede: optimisation methods, evolutionary optimisation methods, genetic algorithms, genetic programming, defibrillation, cardiac arrest prediction, atrial fibrillation, electrical cardioversion, prediction
Objavljeno v DKUM: 01.06.2012; Ogledov: 2159; Prenosov: 81
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Prediction of total manufacturing costs for stamping tool on the basis of CAD-model of finished product
Mirko Ficko, Igor Drstvenšek, Miran Brezočnik, Jože Balič, Boštjan Vaupotič, 2005, izvirni znanstveni članek

Opis: One of the orientations of the tool-making industry is towards shortening the time from enquiry to the supply of tools. The tool-making shops must prepare within the shortest possible time an offer for the manufacturer of the tool based on the enquiry in the form of the CAD-model of the final product. For preparation of a proper offer, the values of certain technological features occurring in the manufacture of the tool are needed. Most frequently the tool manufacturer is interested in total cost for manufacture of the tool. Because of lack of time for making a detailed analysis the total costs of tool manufacture are predicted by the expert on the basis of the experience gathered during several years of work in this area. In our work, we conceived an intelligent system for predicting of total cost of the tool manufacture. We limited ourselves to tools for manufacture of sheet metal products by stamping; the system is based on the concept of case-based reasoning. On the basis of target and source cases, the system prepares the prediction of costs.The target case is the CAD-model in whose costs we are interested, whereas the source cases are the CAD-model of products, for which the tools had already been made, and the relevant total costs are known. The system first abstracts from CAD-models the geometrical features, and then it calculates the similarities between the source cases and target case. Then the most similar cases are used for preparation of prediction by genetic programming method. The genetic programming method provides the model connecting the individual geometrical features with total costs searched for. In the experimental work, we made a system adapted for predicting of tool costs used for tool manufacture on the basis of a theoretic model. The results show that the quality of predictions made by the intelligent system is comparable to the quality assured by the experienced expert.
Ključne besede: intelligent systems, prediction of costs, tool-making, stamping, CAD model, costs, genetic programming
Objavljeno v DKUM: 01.06.2012; Ogledov: 1789; Prenosov: 87
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Flow-pressure analysis of loop gas networks
Jurij Krope, Peter Trop, Darko Goričanec, 2011, izvirni znanstveni članek

Opis: This paper proposes a mathematical model underlying a computer program for flow-pressure analysis of loop gas pipe networks. The method is used on a test case with four nodes. The HAPN application for flow-pressure analyses of low pressure gas pipe networks is completely designed in object-oriented programming technology. The equations, which describe the physical flow-pressure conditions through every cross point are assumed to be continuous and the energy of every closed loop of analyzed network conserved. The system of non-linear equations was linearized by LTM (Linear Theory Method). The algorithm for numerical module LTM and the method for solution of sparse matrix are developed at the Faculty of Chemistry and Chemical Engineering, University of Maribor, Slovenia.
Ključne besede: fluid mechanics, gas pipe networks, linear method, non-linear programming, pressure losses
Objavljeno v DKUM: 01.06.2012; Ogledov: 2232; Prenosov: 33
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Prediction of the ultraviolet protection of cotton woven fabrics dyed with reactive dystuffs
Polona Dobnik-Dubrovski, Miran Brezočnik, 2009, izvirni znanstveni članek

Opis: Textile materials provide a simple and convenient protection against UV radiation. To assign the degree of UV radiation protection of textile materials, the Ultraviolet Protection Factor (UPF) is commonly used. This paper reports the effect of woven fabric construction (yarn fineness, type of weave, relative fabric density), the colour of bi-functional reactive dyestuffs, and Cibacron dyed fabrics on the ultraviolet protection of light summer woven fabrics. A predictive model, determined by genetic programming, was derived to describe the influence of fabric construction. Warp and weft densities, weave factor and CIELab colour components were taken into account by developing the prediction model for UPF. The results show very good agreement between the experimental and predicted values.
Ključne besede: ultraviolet protection factor, woven fabric construction, colour, prediction model, genetic programming
Objavljeno v DKUM: 31.05.2012; Ogledov: 1832; Prenosov: 40
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Yield strength modelling of formed material using evolutionary computational method
Leo Gusel, Rebeka Rudolf, 2009, izvirni znanstveni članek

Opis: In this paper we propose an evolutionary computation approach for the modelling of yield strength in formed material. One of the most general evolutionary computation methods is genetic programming, which was used in our research. Genetic programming is an automated method for creating a working computer program from a problemćs high-level statement. Genetic programming does this by genetically breeding a population of computer programs using the principles of Darwinianćs natural selection and biologically inspired operations. During our research, material was cold formed by drawing using different process parameters and then determining yield strengths (dependent variable) of the specimens. On the basis of a training data set, various different genetic models for yield strength distribution were developed during simulated evolution. The accuracies of the best models were proved by a testing data set and comparing between the genetic and regression models. The research showed that very accurate genetic models can be developed by the proposed approach.
Ključne besede: metal forming, yield strength, genetic programming, modelling
Objavljeno v DKUM: 31.05.2012; Ogledov: 2210; Prenosov: 31
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Is my DSL a modeling or programming language?
Yu Sun, Zekai Demirezen, Marjan Mernik, Jeffrey G. Gray, Barrett Richard Bryant, 2008, objavljeni znanstveni prispevek na konferenci

Opis: It is often difficult to discern the differences between programming and modeling languages. As an example, the term "domain-specific language" has been used almost interchangeably in academia and industry to represent both programming and modeling languages, which has caused subtle misconceptions. The borders between a modeling and programming language are somewhat vague and not defined crisply. This paper discusses the similarities and differences between modeling and programming languages, and offers some suggestions on how to better differentiate such languages. A list of criteria is presented for language classification, but it is suggested that a set of the criteria be used, rather than a single criterion. Several example domain-specific languages are used as case studies to motivate the discussion.
Ključne besede: domain-specific languages, programming languages, modeling language
Objavljeno v DKUM: 31.05.2012; Ogledov: 1687; Prenosov: 43
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Using ontologies in the domain analysis of domain-specific languages
Robert Tairas, Marjan Mernik, Jeffrey G. Gray, 2008, objavljeni znanstveni prispevek na konferenci

Opis: The design stage of domain-specific language development, which includes domain analysis, has not received as much attention compared to the subsequentstage of language implementation. This paper investigates the use of ontology in domain analysis for the development of a domain-specific language. The standard process of ontology development is investigated as an aid to determine the pertinent information regarding the domain (e.g., the conceptualization of the domain and the common and variable elements of the domain) that should be modeled in a language for the domain. Our observations suggest that ontology assists in the initial phase of domain understanding and can be combined with further formal domain analysis methods during the development of a domain-specific language.
Ključne besede: domain-specific languages, programming languages, ontology, domain analysis
Objavljeno v DKUM: 31.05.2012; Ogledov: 1517; Prenosov: 137
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